Cleaning arrangement for electrostatic precipitator



July 20, 1965- w. B. DAILY ETAL CLEANING ARRANGEMENT FOR ELECTROSTATIC PRECIPITA'I'OR Filed Feb. 13, 1962 wzim United States Patent corporation of Delaware Filed Feb. 13, 1962, Ser. No. 172,990 3 Claims. (Cl. 55-117) The prevent invention relates to gas cleaning apparatus and particularly to an arragnement for an electrostatic precipitator that provides for continuous trouble-free separation of dust particles from a gas stream while it simultaneously permits eflicient removal of the collected dust particles from the collecting surfaces of the precipitator.

In gas cleaning apparatus of the electrostatic type, dust laden gases are directed through a strong electric field between discharge electrodes and grounded collecting surfaces. As the dust particles entrained in the gas stream become electrically charged they move, under the influence of the strong electric field, to the grounded collecting surfaces upon which they are deposited.

In order that the gas cleaning apparatus may be maintained at a high operating efficiency, it is of primary importance that all electrodes and collecting surfaces be periodically subjected to a cleaning action capable of removing the deposited particles to thereby present a relatively clean surface to the incoming dust entrained gas. Since the operating etficiency of gas cleaning apparatus is dependent to a large extent, upon the efliciency with which the deposited particles are removed from the collecting surfaces of the precipitator, it is an object of this invention to provide an arrangement for efficiently removing the deposited particles from the collecting surfaces and subsequently preventing their re-entrainment in the clean gas issuing from the precipitator.

A further object of this invention is to divide the collecting surfaces into zones of maximum and minimum collection whereby those zones of maximum collection may be readily subjected to a more intense cleaning action than those zones of lesser collection.

A still further object of this invention is to provide an electrostatic precipitator having collecting surfaces arranged to provide an efficient cleaning action even though certain of the surfaces are incapacitated due to plugging or fiashover.

These and other objects of our invention will become more apparent when read in conjunction with the accompanying drawings in which:

FIGURE 1 shows a perspective view, partially broken away, of an electrostatic precipitator constructed in accordance with the invention.

FIGURE 2 shows an enlarged view of the relationship between elements that comprise a flow directing means.

In the drawing the numerals l0 and 12 represent spaced collecting sections of an electrostatic precipitator that comprises a series of banks of collecting compartments 14 formed by parallel division plates 16 and 17 that lie in perpendicular planes. Mutually adjacent ends of collecting sections and 12 are aligned with transition sections 22 and 24 that are similarly divided into compart ments contiguous with those of the collecting sections and formed to terminate in perforate surfaces 26 extending arcuately to combine with imperforate arcuate surfaces 28 and form therewith a cylindrical plenum chamber across which gas must flow on its passage between the spaced collecting sections of the assembly.

Each of the collecting sections 10 and 12 is provided with discharge electrodes (not illustrated) in the customary manner to ionize the dust particles carried by the gas through the collecting sections and cause them to 3,152.93 Patented July 20, 1965 move toward and bev deposited upon the surface of the grounded compartment walls.

A cylindrical discharge duct 32 is mounted concentrically within the cylindrical plenum chamber on hearing means 34 positioned at opposite ends of the chamber. The bearing means include a suitable drive arrangement for rotating the cylindrical duct slowly about its axis. A plurality of axially contiguous but circumferentially displaced branch ducts 38 depend from the duct 32 and extend radially into a closely spaced relationship with the perforate surface 26 whereby the ends of the compartments 14 in the transition sections are axially aligned with the ends of theducts 38. Thus rotation of the cylindrical duct 32 with its depending branch ducts 38 about its central axis will sequentially bring each branch duct 38 into communication with aligned compartments 14 of collecting sections 10 and 12 whereby gas from one of said compartments may be drawn to its aligned branch duct 38, central duct 32 and thence to outlet duct 42 by an induced draft fan (not shown) as indicated by the arrow '45.

In order that only the collecting compartments 14 of a single section 10 or 12 may be subjected to a cleaning action at 'any given time, a valving arrangement is provided intermediate the end of the cylindrical duct 32 and the outlet duct 42 that houses the induced draft fan whereby the duct; 42 may be closed to a predetermined one of said collecting sections 10 or 12. The valving arrangement comprises essentially a pair of dampervalves 44 and 46 of the butterfly type that lie in the bifurcated ends 52, 54 of the outlet duct 42 and are arranged to cooperate with a valving arrangement lying intermediate the ends of the duct sections 52, 54 and the rotary cylindrical duct 32.

More particularly the end opening of each bifurcated section 52, 54 confronts a portion of a plane end plate 56 formed with a pair of diametrically spaced sectorial openings 58, one of which is centrally spaced in each of said ducts 52 and 54 to permit access between said ducts and the cylindrical duct 32.

The cylindrical duct 32 is divided by four radial plates 62 into four sectorial compartments, each of which having but a single radial outlet through a branch duct 38 to a specific bank of compartments 14 in the sections 10 and 12.

Since circumferentially adjacent ducts 38 are perpendicular to one another and to the central duct 32 it is apparent that the end openings of the horizontally positioned ducts 38 each confront an imperforate arcuate surface 28 of the plenum chamber while those in a vertical position can front the perforate surfaces 26 that lead to the collecting compartments 14. Thus both ducts 38 that lie in a generally horizontal position are necessarily closed to all gas flow While both vertically disposed ducts are open to their respective compartments 14 whereby gas in these compartments may be moved by the exhaust fan to dislodge dust particles deposited on the compartment walls and then discharge them through the outlet duct 42. As the duct 32 is rotated about its axis, one pair of vertically disposed ducts 38 is always in confronting relation with the spaced perforate surfaces of the collecting sections 10 and 12, but by selectively opening and closing damper valves 44 and 46 either the upper or lower duct 38 may be effectively closed to gas flow to limit the purging or cleaning action by the open duct 38 to a single section 10 or 12.

In the arrangement illustrated in the drawing, the upper damper 44 is closed and the lower damper 46 is open to permit gas moved by the fan to contact the dust particles deposited upon the surface of the compartments 14 in lower section 10. By a reversal of the damper a1- rangement that would open damper 44 and close damper The damper valves 44 and '46 maybe operated manually to afford the required cleaning action for the surfaces of the upper or lower collecting sections. However,.it should not be considered beyond the scope of the invention to assume that a conventional motor actuator with timing mechanism might be adapted to control the damper valves 44 and 46 in accordance with prevailing conditions.

While this invention has been described chiefly with respect to the device illustrated in the drawing, it is evident that various changes may be made without departing from the spirit of the invention, and it is intended that all matter contained in the accompanying drawings shall be interpreted as illustrative. and not'in a limiting sense.

We claim: 1. Gas cleaning apparatus comprisingspaced collecting sections of generally rectangular configurations having mutually adjacent surfaces formed arcuately with'spaced openings that lead to independent compartments in said collecting sections, imperforate arcuate walls intermediate said mutually adjacent arcuate surfaces connected thereto to enclose a cylindrical chamber, a cylindrical duct in said chamber concentric therewith and having axially spaced end portions that-terminate adjacent spaced ends of the cylindrical chamber, bearing means supporting the cylindrical duct for rotation about its axis, means dividing said cylindrical duct into"a plurality of sect-orial compartments, branch duct means aligned with axially spaced compartments in the collecting sections depending radially from said sectorial compartments and extending into closely spaced relation with the arcuate surfaces of the cylindrical chamber, means for rotating the cylindrical duct about its'axis, a discharge duct, a birfurcated duct intermediate said discharge duct and spaced compartments of saidcylindrical duct, an end plate carried by said bifurcatedduct inclo'sely spaced relation with an end portion of said cylindrical duct, said end plate having apertures that provide communication between spaced portions of said bifurcated duct and spaced sectorial compartments of the cylindrical duct, and means controlling fluid flow through spaced portions of the'bifurcated duct and the sect-orial compartments of the cylindrical duct communicating-therewith through the apertures of said end plate.

2. Gas cleaning apparatus as defined in claim 1 Wherein the apertures of said end plate are diametrically spaced in line with the arcuate surfaces of the spaced collecting l sections.

3. Gas cleaning apparatus as defined in claim2 wherein the means adapted to precludeair flow through the sectorial compartments comprises a valve in each branch of the bifurcated duct.

References Cited by the Examiner UNITED STATES PATENTS 2,887,176 5/59 Hodson --117 XR HARRY -B.' THORNTON, Primary Examiner. 

1. GAS CLEANING APPARATUS COMPRISING SPACED COLLECTING SECTIONS OF GENERALLY RECTANGULAR CONFIGURATIONS HAVING MUTUALLY ADJACENT SURFACES FORMED ARCUATELY WITH SPACED OPENINGS THAT LEAD TO INDEPENDENT COMPARTMENTS IN SAID COLLECTING SECTIONS, IMPERFORATE ARCUATE WALLS INTERMEDIATE SAID MUTUALLY ADJACENT ARCUATE SURFACES CONNECTED THERETO TO ENCLOSE A CYLINDRICAL CHAMBER, A CYLINDRICAL DUCT IN SAID CHAMBER CONCENTRIC THEREWITH AND HAVING AXIALLY SPACED END PORTIONS THAT TERMINATE ADJACENT SPACED ENDS OF THE CYLINDRICAL CHAMBER, BEARING MEANS SUPPORTING THE CYLINDRICAL DUCT FOR ROTATION ABOUT ITS AXIS, MEANS DIVIDING SAID CYLINDRICAL DUCT INTO A PLURALITY OF SECTORIAL COMPARTMENTS, BRANCH DUCT MEANS ALIGNED WITH AXIALLY SPACED COMPARTMENTS IN THE COLLECTING SECTIONS DEPENDING RADIALLY FROM SAID SECTORIAL COMPARTMENTS AND EXTENDING INTO CLOSELY SPACED RELATION WITH THE ARCUATE SURFACES OF THE CYLINDRICAL CHAMBER, MEANS FOR ROTATING THE CYLINDRICAL DUCT ABOUT ITS AXIS, A DISCHARGE DUCT, A BIRFURCATED DUCT INTERMEDIATE SAID DISCHARGE DUCT AND SPACED COMPARTMENTS OF SAID CYLINDRICAL DUCT, AN END PLATE CARRIED BY SAID BIFURCATED DUCT IN CLOSELY SPACED RELATION WITH AN END PORTION OF SAID CYLINDRICAL DUCT, SAID END PLATE HAVING APERTURES THAT PROVIDE COMMUNICATION BETWEEN SPACED PORTIONS OF SAID BIFURCATED DUCT AND SPACED SECTORIAL COMPARTMENTS OF THE CYLINDRICAL DUCT, AND MEANS CONTROLLING FLUID FLOW THROUGH SPACED PORTIONS OF THE BIFURCATED DUCT AND THE SECTORIAL COMPARTMENTS OF THE CYLINDRICAL DUCT COMMUNICATING THEREWITH THROUGH THE APERTURES OF SAID END PLATE. 